US military grounds all F-35 fighter jets

U.S. military officials have grounded all F-35s while continuing to investigate a runway fire involving one of the fighter jets at Eglin Air Force Base in Florida.

In a statement issued Thursday, the Pentagon's press secretary said Air Force and Navy officials ordered the F-35 fleet grounded after initial findings in the incident in Florida on June 23.

Officials said at the time that the jet caught fire during takeoff at Eglin Air Force Base. No one was hurt, and the cause remains under investigation.

The Pentagon says that additional inspections of F-35 engines have been ordered, and that the return to flight of the F-35 fleet will be determined based on inspection results and analysis of engineering data.

The June 23 incident was the latest to hit the Pentagon's costliest weapons program, the $398.6 billion F-35 Joint Strike Fighter. It followed an in-flight oil leak that triggered mandatory fleetwide inspections of the jets last month. Last year, the military suspended all test flights for the aircraft as “a precautionary measure” after a crack was discovered on a turbine blade in one F-35 engine at Edwards Air Force Base in California.

The warplane's single engine is built by Pratt & Whitney, which said it was working closely with Air Force officials who are investigating the fire to determine the cause of the incident and inspect all engines in the fleet. Spokesman Jay DeFrank said it would be inappropriate to comment further since the incident was the subject of an investigation.

A person familiar with the situation said it was premature to rule in or out any quality problem or manufacturing defect.

Wire services